Unwanted or inadequate eye movements impair vision. By neurological evaluation we can sometimes localize the damage causing eye movement disorders. Our method is to combine in selected cases the best neurological evaluation possible with quantitative recording of eye movement responses to calibrated vestibular, optokinetic, and discrete visual stimuli. Eye movements are recorded by electro-oculography or infrared oculography, and response parameters are analyzed by computer. We have studied patients with cerebellar disease, myasthenia gravis, internuclear ophthalmoplegia, and epileptiform eye movements. Cerebellar eye movement disorders can be classified into proprioceptive and visual disturbances, and appear to correlate with mid-vermal and posterior vermal damage. We have outlined the features which distinguish Myasthenia Gravis from other conditions with similar presentations. We have modeled internuclear ophthalmoplegia as impaired excitation of ipsilateral medial rectus with partial impairment of contralateral lateral rectus.